The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structures.
In the past, the semiconductor industry utilized various methods and structures to produce level shifter circuits that shifted the logic levels of a digital signal from one set of voltage values to a different set of voltage values. These level shifter circuits had various applications such as in circuits that communicated among one another with a serial communication protocol. In such applications, the communication signal may be transmitted from a circuit that operated between one set of voltage levels and may be received by circuit that operated between a different set of voltage levels. Some of the prior level shifter circuits required dual power supplies in order to translate the incoming signal to the voltage level of the receiving circuit. Using dual power supplies usually increased the cost of the circuits.
Other level shifter circuits sank current from the input signal which could have degraded the input signal and resulted in errors in the received signal. Some other level shifters consumed dc current which caused power dissipation during periods when most of the circuit was not switching, such as during a standby operating mode.
Accordingly, it is desirable to have a method of forming a level shifter circuit that minimizes the amount of current sunk from the input signal, that does not require dual power supplies, that minimizes power dissipation, and that reduces the cost of the level shifter circuit.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action.